mini - Many questions from xperienced Windows user just got a Mac :)

Brief intro before I ask all you mac guru's a lot of simple questions if you don't mind...

Been wanting to get a media centre PC in my living room so I could watch divx/xvid epsidoes of my fave programs on my nice big 42" plasma tv, having looked around for months I just cannot justify the money needed to get something reasonable in a SMALL/QUIET box.

Figured the lovely Mac Mini (superdrive) model could do all that I wanted so I went out yesterday and bought one!!! I am very very pleased with it so far, configuration was easy, on the internet with my PC's wifi router in minutes, I installed VLC Media Player and can already play all movie formats I need, stream radio via iTunes and surf the net, love the interface already, not read any manuals, I'm a tecchy who just loves to work all this stuff out, so far no problems.

Questions please...

1) I'm behind a NAT router, currently use the excellent OutPost firewall on my PC, do I need a firewall on the mac? How do I control what programs are connected outbound etc??? Recommendations?

2) I'll be using my PC for emails, just pure surfing on the mac, again do I need an Anti-Virus? Recommendations please, no Symantec tho!

3) Do I need to defrag the drive at all on the mac? If so, again please recommend a good tool for this, I know nothing about the mac tools compared to knowing almost every PC tool around!

4) I'm using the bluetooth wireless keyboard/mouse, if I click the bluetooth icon on the desktop and turn "discoverable" to OFF will I lose my keyboard/mouse connection - for security I want it off.

5) I use Mozilla Firefox on my PC with lots of excellent extensions, I presume I can install the mac version of Firefox and will all my .xpi extensions just work the same?

6) Does the mac use a dreaded Registry like WindowsXP or is everything in nice prefs files (I suspect)?

7) I tweak every inch of my WindowsXP to get the best performance out of it, would I benefit at all with my mac mini if I was to partition the drive or change the size of the paging file or anything? Any good tweaks that help squeeze a bit more out of it?

Thanks all, I've probably got a lot more questions the more I use it, these are the ones I can think of for now

Get a mighty mouse, Where did you get a one-button Apple mouse? I didn't think Apple stores sold them anymore.

I got the bluetooth wireless keyboard/mouse as this is for the living room so sat quite a distance away from the mac mini hardware. They don't do a wireless mighty mouse yet do they?
When they do I'll be first in the queue!

Don't forget to add Front Row to your Mini! Front Row is a basic media center frontend for Macs; it lets you watch DVDs, movies, and photos as well as listen to music. I'm running it on my G4 Cube with excellent results. Info here: